The use of a co-extrusion apparatus to manufacture various structures has been discussed in several patent applications and issued patents. A co-extrusion apparatus is one in which two or more materials are extruded simultaneously into a structure of some kind. This type of apparatus can be used in fabrication of batteries, simultaneously extruding electrodes with separators to form components of batteries.
Examples of the co-extrusion approaches include US Patent Publication 20120156364, in which interdigitated fingers of co-extruded materials are extruded from one print head type of apparatus. The materials are fed into feeding channels and combined as separate flows, then split and combined again until a structure of alternating stripes of the two materials is created as they exit the print head. In another approach, the side-by-side lateral structure extends to interdigitated stripes in the vertical direction as well. US Patent Publication 20140186519 teaches a means to generate this type of structure.
The use of these structures to fabricate batteries is discussed in other publications, such as U.S. Pat. No. 5,714,278, in which a masked portion of the area of a porous separator material used in a battery. Masked areas can be formed on the porous separator material and allows for easier alignment of the anode and cathode sections to avoid edge effects. However, these areas are not formed in co-extrusion print heads.
US Patent Publication No. 20110217585 discusses batteries having integrated separators and methods of fabricating such batteries. The separators are formed in different ways, but generally formed directly on either the cathode or anode. The separators may be single layer or multi-layered. These approaches do not form the electrodes and separators simultaneously in an extrusion manner.
Another approach uses electrophoretic deposition in sequential layers to form thin-film batteries. The sequential layers are formed using electrophoretic deposition. An example of this approach is shown in US Patent Publication 20130244102.
None of these approaches form the electrodes and separators simultaneously using a co-extrusion print head. These types of print heads have several advantages in their simplicity, their simultaneous deposition capability, but none exist that can form separator structures simultaneously with the electrodes. Because they are not formed simultaneously, the separator cannot be formed to be truly conformal to the electrode. Having a conformal separator provides a layer around the electrode to prevent the battery from shorting.